Radiation detection technology is being deployed worldwide to address concerns regarding the illicit movement of radiological and nuclear materials. Equipment of different types and from various manufacturers is being distributed to operators with varying levels of training and different backgrounds. There is a need to reliably exercise and demonstrate the capabilities of these detectors and responders. In particular: (1) many detector developers, manufacturers, and vendors do not have weapons-grade plutonium, WGPu, for testing their hardware or isotope identification algorithms; (2) since the identification of shielded or masked plutonium depends on the plutonium radiation intensity and spectrum, a high-fidelity surrogate exhibiting the full WGPu spectrum is needed to test the effects of shielding and masking in different shielding configurations; (3) fixed-site radiation detection equipment (ports, border crossings, etc.) requires in situ testing capability, and (4) nuclear incident response exercises require credible materials.
The use of Nuclear Explosive-Like Assemblies (NELAs) is not always an attractive option for the stated applications, since NELAs typically contain actual SNM combined with inert materials (or conversely, high-explosives combined with non-radioactive materials), and their use is limited to secure facilities. The use of a NELA is prohibitive due to cost, safety and security concerns for all but the most pressing needs. By contrast, a non-SNM surrogate can be transported and deployed without the substantive administrative controls required for SNM.
Accordingly, it is an object of the embodiments of the present invention to provide a radiation surrogate having a neutron and gamma-ray signature which is representative of the neutron and gamma-ray spectrum of weapons-grade plutonium at an energy resolution of 5% without the use of special nuclear material.
Another object of the embodiments of the present invention is to provide a radiation surrogate having a neutron and gamma-ray signature which is representative of the gamma-ray spectrum of weapons-grade plutonium at an energy resolution 5% over an energy range of 59 keV to 2614 keV without the use of special nuclear material.
Still another object of the embodiments of the present invention is to provide a radiation surrogate having a neutron and gamma-ray signature which is representative of the gamma-ray spectrum of weapons-grade plutonium at an energy resolution 5% over an energy range of 59 keV to 2614 keV without the use of special nuclear material, and having low α-particle emission.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.